/* 
 * PROJECT: NyARToolkit(Extension)
 * --------------------------------------------------------------------------------
 * The NyARToolkit is Java edition ARToolKit class library.
 * Copyright (C)2008-2009 Ryo Iizuka
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * For further information please contact.
 *	http://nyatla.jp/nyatoolkit/
 *	<airmail(at)ebony.plala.or.jp> or <nyatla(at)nyatla.jp>
 * 
 */
package jp.nyatla.nyartoolkit.core.utils;

import jp.nyatla.nyartoolkit.NyARException;
import jp.nyatla.nyartoolkit.core.types.NyARIntPoint2d;

/**
 * 遠近法を用いたPerspectiveパラメータを計算するクラスです。
 *
 */
public class NyARPerspectiveParamGenerator
{
	protected int _local_x;
	protected int _local_y;
	protected int _width;
	protected int _height;
	public NyARPerspectiveParamGenerator(int i_local_x,int i_local_y,int i_width, int i_height)
	{
		this._height=i_height;
		this._width=i_width;
		this._local_x=i_local_x;
		this._local_y=i_local_y;
		return;
	}
	public boolean getParam(final NyARIntPoint2d[] i_vertex,double[] o_param)throws NyARException
	{
		double[][] la1,la2;
		double[] ra1,ra2;
		double ltx=this._local_x;
		double lty=this._local_y;
		double rbx=ltx+this._width;
		double rby=lty+this._height;
		la1=new double[4][5];
		la2=new double[4][5];
		ra1=new double[4];
		ra2=new double[4];
		//A,B,C,(GH)の方程式
		la1[0][0]=ltx;	la1[0][1]=lty;	la1[0][2]=1;	la1[0][3]=-ltx*i_vertex[0].x;	la1[0][4]=-lty*i_vertex[0].x;
		la1[1][0]=rbx;	la1[1][1]=lty;	la1[1][2]=1;	la1[1][3]=-rbx*i_vertex[1].x;	la1[1][4]=-lty*i_vertex[1].x;
		la1[2][0]=rbx;	la1[2][1]=rby;	la1[2][2]=1;	la1[2][3]=-rbx*i_vertex[2].x;	la1[2][4]=-rby*i_vertex[2].x;
		la1[3][0]=ltx;	la1[3][1]=rby;	la1[3][2]=1;	la1[3][3]=-ltx*i_vertex[3].x;	la1[3][4]=-rby*i_vertex[3].x;
		ra1[0]=i_vertex[0].x;ra1[1]=i_vertex[1].x;ra1[2]=i_vertex[2].x;ra1[3]=i_vertex[3].x;
		NyARSystemOfLinearEquationsProcessor.doGaussianElimination(la1,ra1,5,4);

		//D,E,F,(GH)の方程式
		la2[0][0]=ltx;	la2[0][1]=lty;	la2[0][2]=1;	la2[0][3]=-ltx*i_vertex[0].y;	la2[0][4]=-lty*i_vertex[0].y;
		la2[1][0]=rbx;	la2[1][1]=lty;	la2[1][2]=1;	la2[1][3]=-rbx*i_vertex[1].y;	la2[1][4]=-lty*i_vertex[1].y;
		la2[2][0]=rbx;	la2[2][1]=rby;	la2[2][2]=1;	la2[2][3]=-rbx*i_vertex[2].y;	la2[2][4]=-rby*i_vertex[2].y;
		la2[3][0]=ltx;	la2[3][1]=rby;	la2[3][2]=1;	la2[3][3]=-ltx*i_vertex[3].y;	la2[3][4]=-rby*i_vertex[3].y;
		ra2[0]=i_vertex[0].y;ra2[1]=i_vertex[1].y;ra2[2]=i_vertex[2].y;ra2[3]=i_vertex[3].y;
		NyARSystemOfLinearEquationsProcessor.doGaussianElimination(la2,ra2,5,4);
		//GHを計算
		double A,B,C,D,E,F,G,H;
		H=(ra2[3]-ra1[3])/(la2[3][4]-la1[3][4]);
		G=ra2[3]-la2[3][4]*H;
		//残りを計算
		F=ra2[2]-H*la2[2][4]-G*la2[2][3];
		E=ra2[1]-H*la2[1][4]-G*la2[1][3]-F*la2[1][2];
		D=ra2[0]-H*la2[0][4]-G*la2[0][3]-F*la2[0][2]-E*la2[0][1];
		C=ra1[2]-H*la1[2][4]-G*la1[2][3];
		B=ra1[1]-H*la1[1][4]-G*la1[1][3]-C*la1[1][2];
		A=ra1[0]-H*la1[0][4]-G*la1[0][3]-C*la1[0][2]-B*la1[0][1];
		o_param[0]=A;
		o_param[1]=B;
		o_param[2]=C;
		o_param[3]=D;
		o_param[4]=E;
		o_param[5]=F;
		o_param[6]=G;
		o_param[7]=H;
		return true;
	}
}
